OBJECTIVES: The purpose of the research is to elucidate the function of certain lymphokines in the regulation of normal hematopoiesis and in myeloproliferative disorders such as leukemia. APPROACH: We will isolate and characterize a granulocyte-macrophage colony stimulating factor (G,M - CSF) and an erythroid potentiating activity (EPA) from medium conditioned by a human T-cell line. Using the purified, labeled factors we wll study their mode of action. In particular, we will examine whether they act by binding to cell surface receptors; whether lymphokine binding or metabolism is altered in leukemic cells; and whether the factors are internalized and degraded by cells.